CHAPTER7SOLUTIONS MANUALIonic Compounds and MetalsSection 7.1 Ion Formationpages 206–209Section 7.1 Assessmentpage 209c. barium[Xe]6s2; lose 2 electrons (2 ion)d. lithium[He]2s1; lose 1 electron (1 ion)1. Compare the stability of a lithium atom withthat of its ion, Li .The Li ion is more stable because it has acomplete octet.2. Describe two different causes of the force ofattraction in a chemical bond.The two causes are the attraction between thepositive nucleus of one atom and the negativeelectrons of another atom, and the attractionbetween positive ions and negative ions.3. Apply Why are all of the elements from groupCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.18 relatively unreactive, whereas those in group17 are very reactive?The group 18 elements, known as noble gases,have complete outer energy levels and do noteasily form ions. The group 17 elements are highlyreactive because they need only to gain a singleelectron to form an octet.4. Summarize ionic bond formation by correctlypairing these terms: cation, anion, electron gain,electron loss.{anion, electron gain}, {cation, electron loss}6. Model Draw models to represent the forma-tion of the positive calcium ion and the negativebromide ion.Models should show that the calcium atom losestwo electrons, forming Ca2 , and that brominegains one electron, forming Br . The modelsshould also show the addition of energy to formthe calcium ion, and the release of energy to formthe bromide ion.Section 7.2 Ionic Bonds and IonicCompoundspages 210–217Practice Problemspage 212Explain how an ionic compound forms from theseelements.7. sodium and nitrogenThree Na atoms each lose 1 e , forming 1 ions.One N atom gains 3 e , forming a 3 ion. Theions attract, forming Na3N.3 Na ions5. Apply Write out the electron configurationfor each atom. Then predict the change that mustoccur in each to achieve a noble gas configuration.a. nitrogen[He]2s22p3;gain 3 electrons (3 ion) or lose5 electrons (5 ion)b. sulfur[Ne]3s23p4; gain 2 electrons (2 ion)3 1 1 N ion ( )(Na ion )N ion 3(1 ) 1(3 ) 0The overall charge on one formula unit of Na3Nis zero.8. lithium and oxygenTwo Li atoms each lose 1 e , forming 1 ions.One O atom gains 2 e , forming a 2 ion. Theions attract, forming Li2O.2 Li ions1 2 1 O ion ( )(Li ion )O ion 2(1 ) 1(2 ) 0The overall charge on one formula unit of Li2Ois zero.Solutions ManualChemistry: Matter and Change Chapter 7103

7SOLUTIONS MANUAL9. strontium and fluorine13. Describe the energy change associated withe ,One Sr atom loses 2forming a 2 ion. Two Fatoms each gain 1 e , forming 1 ions. The ionsattract, forming SrF2.1 Sr ion2 1 2 F ions ( )(Sr ion )F ion 1(2 ) 2(1 ) 0The overall charge on one formula unit of SrF2is zero.10. aluminum and sulfurTwo Al atoms each lose 3 e , forming 3 ions.Three S atoms gain 2 e each, forming 2 ions.The ions attract, forming Al2S3.2 Al ions3 2 3 S ions ( )(S ionAl ions ) 2(3 ) 3(2 ) 0ionic bond formation, and relate it to stability.Ionic bond formation is exothermic; the lowerenergy product is more stable than the originalreactants.14. Identify three physical properties of ioniccompounds that are associated with ionic bonds,and relate them to bond strength.Ionic compounds exist as crystals, have highmelting and boiling points, and are hard,rigid, and brittle. They are conductive whendissolved or molten but not when solid. All ofthese properties are due to the strength of theelectrostatic attraction of oppositely-charged ionsin close proximity.15. Explain how ions form bonds and describe thestructure of the resulting compound.The overall charge on one formula unit of Al2S3is zero.11. Challenge Explain how elements in the twogroups shown on the periodic table at the rightcombine to form an ionic compound.Group 15Group 1Electrons are transferred between atoms formingions. Electrostatic forces hold the ions together inthe ionic compound. The ions are arranged in aregular repeating pattern in an ionic crystal.16. Relate lattice energy to ionic-bond strength.As lattice energy becomes more negative, thestronger is the attraction between the ions and,thus, the stronger the ionic bond.17. Apply Use electron configurations, orbitale ,Three group 1 atoms loses 1forming 1 ions.One group 15 atom gains 3 e , forming a 3 ion.The ions attract, forming X3Y, where X represents agroup 1 atom and Y represents a group 15 atom.Section 7.2 Assessmentpage 217notation, and electron-dot structures to representthe formation of an ionic compound from themetal strontium and the nonmetal chlorine.Drawing should include one Sr atom losing 2 e and forming an Sr2 ion, and two Cl atoms eachgaining 1 e and forming two Cl ions. Theseions attract, forming SrCl2.12. Explain how an ionic compound made up ofcharged particles can be electrically neutral.The total positive charge of the cations in thecompound equals the total negative charge of theanions in the compound.104Chemistry: Matter and Change Chapter 7Solutions ManualCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.CHAPTER

7SOLUTIONS MANUALElectron Configuration[Ne]3s23p5[Kr]5s2 [Ne]3s23p52Cl Orbital Notation e Sr2 2Cl Sr[Ar][Kr] [Ar] CHAPTER 3p 2Cl 3s 2p 1s 2se 5s3p 4p 3d3s 4s 3pSr2p 3s 2p 1s 2s 1s 2s 1s 2s2p3s2Cl 3p 3p[ Cl ] [ Cl ] 18. Design a concept map that shows the rela-tionships among ionic bond strength, physicalproperties of ionic compounds, lattice energy,and stability.Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.3s 2p [Sr]2 1s 2s e Cl 4p Sr3d Electron-dot Structures e Cl3p4sSr2 3s 2p 1s 2sConcepts maps will vary but should correlategreater bond strength to increased stability anda more negative lattice energy, and that physicalproperties such as high melting and boilingpoints, brittleness, and conductivity are due tothe strength of ionic bonds.21. aluminum and bromideAlBr322. cesium and nitrideCs3N23. Challenge Write the general formula for theionic compound formed by elements fromthe two groups shown on the periodic tableat the right.Group 17Section 7.3 Names and Formulasfor Ionic CompoundsGroup 2pages 218–224Practice Problemspages 221–223Write formulas for the ionic compounds formed bythe following ions.19. potassium and iodideKI20. magnesium and chlorideThe general formula is XY2, where X representsthe group 2 element and Y represents the group17 element.Write formulas for ionic compounds composed ofthe following ions.24. sodium and nitrateNaNO3MgCl2Solutions ManualChemistry: Matter and Change Chapter 7105

7SOLUTIONS MANUALSection 7.3 Assessment25. calcium and chloratepage 224Ca(ClO3)234. State the order in which the ions associated26. aluminum and carbonatewith a compound composed of potassium andbromine would be written in the chemicalformula and the compound name.Al2(CO3)327. Challenge Write the formula for an ioniccompound formed by ions from a group 2element and polyatomic ions composed of onlyof carbon and oxygen.2 ).The polyatomic ion is carbonate (CO3The general formula is XCO3, where X is thesymbol of a group 2 element.Name the following compounds.28. NaBrsodium bromide29. CaCl2calcium chloride30. KOHpotassium hydroxide31. Cu(NO3)2copper(II) nitrate32. Ag2CrO4silver chromate33. Challenge The ionic compound NH4ClO4 iskey reactant used in solid rocket boosters, suchas those that power the space shuttle into orbit.Name this compound.ammonium perchlorateThe cation (potassium) is stated first, followed bythe anion (bromide).35. Describe the difference between a monatomicion and a polyatomic ion and give an exampleof each.Monatomic ions are one-atom ions (example, Cl );polyatomic ions are two or more atoms groupedtogether having a net charge (example, ClO3 ).36. Apply Ion X has a charge of 2 and ion Y hasa charge of 1 . Write the formula unit of thecompound formed from the ions.XY237. State the name and formula for the compoundformed from Mg and Cl.magnesium chloride, MgCl238. Write the name and formula for the compoundformed from sodium ions and nitrite ions.sodium nitrite, NaNO239. Analyze What subscripts would you mostlikely use if the following substances formed anionic compound?a. an alkali metal and a halogen1, 1b. an alkali metal and a nonmetal from group 162, 1c. an alkaline earth metal and a halogen1, 2d. an alkaline earth metal and a nonmetal fromgroup 161, 1106Chemistry: Matter and Change Chapter 7Solutions ManualCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.CHAPTER

CHAPTER7Section 7.4 Metallic Bonds andthe Properties of Metalspages 225–228Section 7.4 Assessmentpages 22840. Contrast the structures of ionic compoundsand metals.Ions in ionic compounds are arranged in arepeating pattern of alternating charges, whereasmetals consist of fixed cations surrounded by asea of mobile, or delocalized, electrons.41. Explain how the conductivity of electricity andthe high melting points of metals are explainedby metallic bonding.Delocalized electrons can move through thesolid to conduct an electric current. The numberof delocalized electrons and the strength of ametallic bond determine the melting point.42. Contrast the cause of the attraction in ionicCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.bonds and metallic bonds.Ionic bonds are held together by the electrostaticforce of attraction between ions, whereas ametallic bond is due to the attraction of metalliccations for delocalized electrons.43. Summarize alloy types by correctly pairingthese terms and phrases: substitutional, interstitial, replaced, filled in.{substitutional, replaced}, {interstitial, filled in}44. Design an Experiment Describe an experi-ment that could be used to distinguish betweena metallic solid and an ionic solid. Include atleast two different methods for comparing thesolids. Explain your reasoning.A typical student experiment might have stepssimilar to the following:1. Test each solid with a conductivity tester.2. Place the solid in water to determine if it formsa solution.SOLUTIONS MANUALMetallic solids conduct an electric current in thesolid state, whereas ionic compounds do not.Metals may react with water, but they do notdissolve in water. Solutions containing ioniccompounds conduct an electric current. Metallicsolids are malleable and will deform when struckwith a hammer, whereas ionic compounds arebrittle and will break into pieces when struckwith a hammer.45. Model Draw a model to represent the physicalproperty of metals known as ductility, or theability to be drawn into a wire. Base yourdrawing on the electron sea model shownin Figure 7.11. - - - - - - - - - - - - - - - Diagrams should show metal ions being movedinto a longer, thinner form through a sea ofelectrons.Everyday ChemistryWriting in ChemistrySense of Danger Our sense of taste can detectcertain toxins found naturatlly in plants. Researcgother modern toxins, such as lead and antifreeze,to find out why they don’t eicit a negative responsefrom our taste buds. For more on green chemistry,visit research should cite speculation by scientiststhat becsause humans and their ancestors did notoften encounter elemental lead (or other moderntoxins) in the natural environment, we have evolvedhaving no natural aversion to eating the toxin. Infact, certain lead compounds found in paint (such aslead acetate) have a sweet taste. Research might alsodiscuss how, contrary to the situation with lead, manyplant-produced toxins have a bitter taste. This is likelydue to the fact that humans and plants haveco-evolved for millions of years.3. Test the solution with a conductivity tester todetermine if it conducts an electric current.4. Use a hammer to strike the solid and recordyour observations.Solutions ManualChemistry: Matter and Change Chapter 7107

7CHAPTERSOLUTIONS MANUALChapter 7 Assessment51. The orbital notation of sulfur is shown inpages 232–235Figure 7.15. Explain how sulfur forms its ion.Section 7.1Sulfur gains 2 electrons in the 3p sublevel,forming a complete octet.Mastering Concepts46. How do positive ions and negative ions form?Mastering Problems52. Give the number of valence electrons in anatom of each element:a. cesiumAn atom gains or loses electrons to achieve astable electron configuration.47. When do chemical bonds form?1when a positive nucleus attracts electrons ofanother atom, or oppositely charged ions attractb. rubidium148. Why are halogens and alkali metals likely toc. galliumform ions? Explain your answer.3Halogens need to gain only one electron to havea noble gas electron configuration. Alkali metalsneed to lose one.d. zinc2DAFe. strontium2GECchemical bonds.49. The periodic table shown in Figure 7.14They already have a full, stable outer energylevel.contains elements labeled A–G. For eachlabeled element, state the number of valenceelectrons and identify the ion that will form.54. Discuss the formation of the barium ion.A: three valence electrons Al3 , B: two valenceelectrons Ba2 , C: one valence electron Rb ,D: five valence electrons N3 , E: seven valenceelectrons I , F: eight valence electrons, no ionformed, G: six valence electrons, Se2 55. Explain how an anion of nitrogen forms.Ba will lose two electrons and form Ba2 , whichhas the stable electron configuration of Xe.N gains three electrons, forming N3 , which hasthe stable electron configuration of Ne.50. Discuss the importance of electron affinity and56. The more reactive an atom, the higher its poten-ionization energy in the formation of ions.tial energy. Which atom has higher potentialenergy, neon or fluorine? Explain.Fluorine, because it will easily gain one moreelectron to fill its outer energy level. high electron affinity: atom easily gains anelectron; low ion